This project examines the kinetics of melatonin in relation to human puberty in normal individuals ages 6-30 years, and in children with delayed puberty. Serum, saliva and urine samples are collected at baseline and at frequent intervals after an intravenous infusion of melatonin for determination of concentrations of melatonin and its metabolite, 6- sulfatoxymelatonin. Kinetic parameters are calculated for each subject and comparisons of results are performed by pubertal groups.